Mulched drip irrigation and biochar application reduce gaseous nitrogen emissions, but increase nitrogen uptake and peanut yield.

Nitrous oxide and ammonia emissions from farmland need to be abated as they directly or indirectly affect climate warming and crop yield. We conducted a two-year field experiment to investigate the effect of biochar applied at two rates (no biochar application vs. biochar applied at 10 t ha-1) on gaseous nitrogen (N) losses (N2O emissions and NH3 volatilization), plant N uptake, residual soil mineral N, and peanut (Arachis hypogaea L.) yield under three irrigation regimes: furrow irrigation (FI), drip irrigation (DI), and mulched drip irrigation (MDI). We found that MDI reduced residual (post-harvest) soil mineral N, cumulative N2O emissions, and yield-scaled N2O emissions as compared to FI. Biochar application increased residual soil NO3--N and decreased yield-scaled N2O emissions as compared with the control without biochar application. Under the three irrigation regimes, biochar application decreased cumulative NH3 volatilization and increased plant N uptake and yield compared with the control. Biochar application improved the sustainability of peanut production and could be used to alleviate the environmental damage associated with gaseous N emissions. Where possible, biochar application under MDI in peanut fields is recommended as a management strategy to minimize gaseous N losses.